Magnetic head assemblies which incorporate ferrite cores are widely used in audio, video and data processing systems. Ferrite is known to be brittle and, therefore, during machining and shaping as well as during operation in the sensing of magnetic media, the ferrite edges and corners can be chipped and otherwise eroded. As the ferrite cores are made smaller and narrower to increase data track density, the chipping and erosion problem exponentially increases. Life and output decrease, thereby adding significantly to the cost of maintenance since the heads have to be replaced and to costs of production because the chipped ferrite cores must be rejected.
Ferrite cores have been assembled with ceramic supports or glass layers to add to the structural strength. It has been found as noted in U.S. Pat. No. 4,298,899, which is assigned to the assignee of the present invention, that layers of alumina films deposited on the sides of the ferrite core before insertion into a magnetic head assembly provide a support to the edges of the ferrite core during the lapping process to determine the throat height for the head as well as providing an edge support during the reading and writing of magnetic transitions from magnetic media. However, the deposition of the alumina was performed on one side at a time which led to stressing of the ferrite cores due to the thermal mismatch of the ferrite material and the alumina. This stress is compounded when the alumina is then deposited on the opposite side. This stress decreased the magnetic properties of the ferrite core. Thus the deposition material on the sides of the ferrite core to prevent edge erosion led to a problem of thermal mismatch between the ferrite core and the deposited material during the deposition process, resulting in stress.
An object of the present invention, therefore, is to provide a magnetic ferrite core assembly which has a longer wear life and is less subject to core erosion and deterioration by a new process for depositing the material onto the sides of the ferrite core.